The field of the invention pertains to crossbows. The invention relates more particularly to a system for capturing and releasing a crossbow bowstring by means of a preferably ball-shaped nocking member centrally mounted on the bowstring, wherein a pair of preferably curved surfaces obstructs the nocking member from discharging when in a closed position, and enables a smooth controlled release of the nocking member when in an open position.
It is known for the operation of crossbows to provide a sear or other catch mechanism which maintains a bowstring in a cocked position prior to and in preparation for release by a trigger mechanism. Conventionally, a sear mechanism having a hook-type catch configuration is used to capture the bowstring directly, and a trigger mechanism actuating the sear hook is used to release the bowstring and thereby discharge a loaded arrow. Perhaps the greatest disadvantage of this arrangement, however, is the tendency of the bowstring to experience extensive wear and deterioration due to repeated frictional contact with the sear hook catch. This can lead to inaccuracy when shooting arrows, or even failure of the bowstring itself.
In an effort to reduce and/or prevent wear of bowstrings, nocking members are mounted on bowstrings to engage the nock portion of a tail end of an arrow, and/or provide an intermediate contact surface for pulling and maintaining the bowstring in a cocked state. Representative examples of bowstring nocking members are described in U.S. Pat. Nos. 4,909,233, 5,787,870, and 5,499,620. Additionally, one type of bowstring nocking member in particular is shown in U.S. Pat. No. 5,361,747 having a ball-shaped configuration which fits in a spherically concave receptacle of a nock element at the end of an arrow. This arrangement has several advantages, among which include providing a constant contact surface at all stages of bowstring deflection which prevents an undesirable clamping effect at the nock element. Furthermore, this arrangement has the ability to transfer force on the end of an arrow without generating tilting forces at the end of the arrow which can affect shooting accuracy.
Various types of bowstring release mechanisms have been developed to utilize the particular ball-type bowstring nocking member shown in the ""747 patent, and thereby realize its benefits. One example is shown in U.S. Pat. No. 5,685,286 disclosing a bowstring release device for an archery bow which seizes opposite sides of a ball-shaped nocking member by means of a pair of gripping arms 16, 18 having sockets 22, 24, respectively. Similarly, in U.S. Pat. No. 5,680,851, a release device is shown also having a pair of spring biased gripping arms with a semispherical socket for engaging the spherical ball-shaped nocking member. A notable disadvantage of both the ""286 and ""851 patents, however, is that the rim of each of the sockets may experience substantial wear at the tip portions from sliding against the exiting nocking member.
In summary, therefore, there is a need for a bowstring release mechanism and system designed for use on a crossbow which incorporates a bowstring nocking member preferably having a ball-shaped configuration. Additionally, such a mechanism and system should minimize the frictional wear typically associated with the trigger and bowstring release mechanics of crossbows.
It is therefore an object of the present invention to provide a simple and efficient bowstring release system for crossbows having a nocking member mounted on the bowstring with a preferably ball-shaped configuration to reduce friction and wear on the bowstring.
It is a further object of the present invention to provide an accurate and durable bowstring release system which releases the nocking member in a smooth, and controlled manner, thereby preventing undesirable transverse forces during release, and reducing friction and wear along the contact surfaces of the system.
It is a further object of the present invention to provide a bowstring release system which maintains the bowstring in the cocked position prior to release by frontally obstructing the nocking member without seizing the nocking member or directly contacting the bowstring itself.
The present invention is for a bowstring release system for crossbows having a crossbow frame with barrel and handle portions, and a bow horizontally mounted on a forward part of the barrel portion. The bow has a bowstring with a nocking member mounted thereon for engaging a nock portion of an arrow. The bowstring release system comprises upper and lower catch surfaces positioned near a rearward part of the barrel portion in vertical relation to each other and having a release passage defined therebetween. The bowstring release system also has actuating means for vertically moving the upper and lower catch surfaces relative to each other between a closed position and an open position. In the closed position, the upper and lower catch surfaces block passage of the cocked nocking member through a release passage without seizing the cocked nocking member. And in the open position, the cocked nocking member passes through the release passage to propel the arrow via the nock portion.